Minimum Path Sum Leetcode

Given a m x n grid filled with non-negative numbers, find a path from top left to bottom right which minimizes the sum of all numbers along its path.

Note: You can only move either down or right at any point in time.

这道题属于动态规划，不用考虑绕路的情况，因为从左上角走到右下角，好像没办法绕路走。

不用一开始就考虑bfs和dfs，复杂度会很高啊。。。

public class Solution {
    public int minPathSum(int[][] grid) {
        if (grid == null || grid.length == 0 || grid[0].length == 0) {
            return 0;
        }
        for (int i = 0; i < grid.length; i++) {
            for (int j = 0; j < grid[i].length; j++) {
                if (i != 0 && j == 0) {
                    grid[i][j] = grid[i - 1][j] + grid[i][j];
                } else if (i == 0 && j != 0) {
                    grid[i][j] = grid[i][j - 1] + grid[i][j];
                } else if (i != 0 && j != 0) {
                    grid[i][j] = Math.min(grid[i][j - 1], grid[i - 1][j]) + grid[i][j];
                }
            }
        }
        return grid[grid.length - 1][grid[0].length - 1];
    }
}

还是回顾一下吧。。。